Monkeypox vaccines: what’s available and why they aren’t a silver bullet

In July 2022 the World Health Organization declared the recent current monkeypox outbreak a global health emergency. Since the start of the year thousands of cases have been reported from over 80 countries. The current outbreak is unlike any previous ones. Infections are happening in non-endemic countries outside of Africa. And the pattern is of sustained person-to-person transmission. But there has also been an increase in the number of cases in countries in west and central Africa where the disease is endemic. The current outbreak monkeypox virus strain has a relatively low mortality compared to other strains. If other strains escape Africa the problem is going to be far more challenging. The Conversation Africa spoke to virologist Anna-Lise Williamson about monkeypox vaccines and best way forward for African countries.

Are there vaccines against Monkeypox? How effective are they?

The monkeypox virus is related to variola virus which caused smallpox and so the smallpox vaccines also protected from monkeypox. But these early smallpox vaccines are no longer commercially available because the disease was certified as eradicated in 1980 and so vaccination stopped.

For a long time monkeypox was rare because of the cross-protection provided by the smallpox vaccine.

There are now two types of vaccine available.

The first is based on a replicating vaccinia virus and formed the basis of the smallpox virus eradication campaigns. This required one immunisation and gave protection for life.

These vaccines are not regarded as very safe because they can have serious side effects. In some cases 1 to 2 people per million vaccinated died of vaccine complications.

This was acceptable in the days of smallpox because about 30% of people who got the disease died from it.

The vaccine faces additional challenges in the era of HIV. People with certain immunodeficiency diseases, including HIV, can’t receive this type of vaccine.

The second vaccine is based on an attenuated form of vaccinia virus called modified vaccinia Ankara (MVA) which cannot complete its replication cycle in humans. This is a very safe vaccine. But protection does not last as long as the conventional vaccines based on replicating vaccinia virus.

It is marketed in the US as Jynneos and in Europe as Imvanex. It requires two immunisations. Both are made by Bavarian Nordic.

As far as I am aware it is uncertain how long people remain protected from infection.

How widely available are the vaccines?

The MVA based vaccine – which is the safest vaccine – appears to be in very short supply. According to newspaper articles Bavarian Nordic are not able to produce the vaccines at present.

There are stockpiles of the vaccinia virus replicating vaccines. But they can’t be rolled out in countries with a high prevalence of HIV without extensive management ensuring HIV-positve people do not get it. South Africa is an example.

Vaccines are key to controlling a number of diseases. Is this true for monkeypox too?

Vaccines are the only way to control monkeypox once you have outbreak as we’re currently seeing in the US and several European countries.

The problem is the cost. Countries have to weigh up the cost of vaccinating everybody versus the cost of treating the disease.

The cost/benefit analysis is different for each country. The scenarios will look very different depending on whether you’re sitting in London or in Lagos. Vaccinating high risk populations is a possible strategy to stop the spread of the disease.

Nigeria has been managing monkeypox outbreaks for some time. But the strategy has not relied on vaccines because, from their viewpoint, it wouldn’t be cost effective. You’d have to vaccinate a lot of people for it to be effective. It obviously makes sense to make sure there’s good disease surveillance.

There is also an antiviral drug, tecovirimat (TPOXX) that has been developed for smallpox and works for treating monkeypox. However this is not available in Africa and so Africa needs to manufacture drugs for the continent.

For developed countries, it makes sense to do contact tracing and to identify high risk communities. And then to vaccinate at-risk populations. This is true particularly if you can’t change people’s behaviour.

What’s the longer term solution for African countries?

African countries must start making the vaccines that they need. For example there’s a vaccine – a recombinant vaccine based on MVA – in final trials that addresses both monkeypox and respiratory syncytial virus (RSV). RSV kills millions of children in Africa every year. If you could vaccinate against both at the same time that may be cost effective.

I belong to Partnerships for African Manufacturing, an initiative that’s pushing for local production capacity.

But it’s hard. We have virtually no expertise. And it requires a great deal of work to set up manufacturing capability.

And it’s going to cost money. Those who have money to invest need to do that.

After the flu pandemic in 2010 everyone said African countries should manufacture flu vaccines. Africa didn’t get any vaccines until the pandemic had ended – a forerunner to the COVID situation.

The danger is that the issue just disappears again and nothing gets done. We must try and keep some momentum in place so we can look after ourselves for next pandemic.